When receiving a signal, such as voice, the signal may be a signal in which signals generated from two or more different sources are mixed. Accordingly, it is necessary to separate or extract only a signal from a desired source from the signal in which signals from two or more sources are mixed. To this end, a blind signal separation (BSS) method and a blind source extraction (BSE) method are known.
In accordance with to the BBS method, signals from two or more sources are separated to separately acquire a signal from each source. However, in the BSS method, a signal from an undesired source, for example, noise is separated, causing an unnecessary increase in the amount of computation, an increase in time of computation, and complexity in circuit configuration.
On the other hand, in accordance with the BSE method, only a signal from a desired source is extracted from signals. However, unless a source to be selected is not defined, uncertainty inevitably occurs. In other words, when only a signal from one source is selectively extracted in a state where an accurate reference is not provided, it may be difficult to ensure that an extracted signal is a desired signal.
A BSE method is also known in which a reference signal is acquired, and one signal is extracted on the basis of the reference signal. In this method, however, there is a problem, in that an additional arithmetic operation is required so as to acquire the reference signal.